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12 - Troubleshooting
In RF notch mode, the red notch guides do not appear
There are two possible causes of this.
First, if the Noise BLanker is set to then the guides are disabled due to the RF signal chain being split prior to the display processing. Set or to resolve this.
Second, if the Notch RF Frequency Lock is set to then the RF notch frequency may be off screen, and so not visible, and and cannot be changed because it is locked. Set to resolve this.
Off center on the spectrum, signals become progressively offset in frequency
This symptom is known to be a result of the SDR's actual sample rate not matching what SdrDx thinks it is. Some SDRs, when commanded by SdrDx to set sample rate "X", will only do so if that rate exactly matches one they can handle. Otherwise, they will typically set to a sample rate as close as they can manage to what SdrDx actually requested, "Y", and this results in inaccuracy in the math that figures out where signals are on the spectrum because SdrDX assumes the SDR is running at the "X" rate it weas told to run at, when it is actually running at "Y."
To correct this, you have to (a) determine what sample rate your SDR is actually running at, or wants to run at, and then (b), make sure SdrDx is set to that exact sample rate.
You can set custom sample rates in the SDR dialog, opened with the button at the lower left.
There is a tuning offset in only one demodulator mode
In , , and , you can right-click the mode button to see if a programmed offset is present.
In , , , , and , the setting of CWO
can impose an offset of up to +/- 999 Hz. Make sure it is set to zero for no offset.
I deleted my preferences, but nothing has changed
Versions of OS X after 10.6.8 have been extremely (and inappropriately) increasingly aggressive about caching application preferences. You can delete or manually replace the preferences file with one you have archived elsewhere, restart SdrDx, and OS X may still use the old version, which is stuck in memory. So don't try to reset your settings that way.
Instead, use the "Reset ALL settings and exit" menu command in the File menu. This will give you a totally clean restart.
WFM stations aren't being received in FM Stereo
There are two possible issues. First and most simple, make sure that is off.
If that doesn't solve the issue, then check to make sure you have your SDR set to a sample rate that it can actually run at. For instance, the AFEDRI AFE822x can't run at 768 KHz. But if you force SdrDx to try to set it to 768 KHz, SdrDx will assume that you know what you're doing, and that the sample rate change worked. Consequently the SDR is now running at a slightly different rate than SdrDx assumes it is; that, in turn, skews the demodulated frequencies enough to disable stereo detection of the FM stereo subcarrier. Other subtle frequency and bandwidth related errors will also occur. Returning the SDR to a rate it can sample at will solve the problem.
The waterfall / spectrum goes bright on changing frequency, as if there's some kind of AGC being applied
There's no default spectrum / waterfall AGC. However, there are several switchable features that do implement waterfall AGC. Make sure that , , , and are all off. In the case of using the memories, the control tells the memory subsystem whether to change the waterfall intercept on memory recall. In the case of using VFOs, within the VFO dialog ( →Right-click any VFO) the Spectrum, dB/Div, and 
Max dB and their associated Ind. checkboxes control the behavior of the VFO bandstack with regard to changing the spectrum and waterfall levels.
Audio distorted sometimes, or other random performance
Are you using Wifi to connect to the SDR? WiFi connections are subject to random delays as other devices demand bandwidth on the WiFi channel; Since WiFi can only carry one connected device at a time, once a device acquires the channel, everything else has to wait. Ethernet is much better at sharing time between devices. Several things can be done:
- Turn off all other WiFi devices.
- It's good to be close to the wifi station, as this increases throughput.
- Reduce your bandwidth as much as possible - the less data per second, the more likely you are to get all the packets you're supposed to get.
- Consider a USB-to-Ethernet adapter for your computer, so you can be directly connected to the network (these are not as reliable as actual ethernet ports, but they're way better than WiFi)
GUI stalls when SdrDx GUI is not used for a while
solution: Turn on the "Twitch" setting in the dialog; this is a work-around to deal with some problems with Apple's display drivers for some graphics hardware.
The problem with some graphics hardware is that when SdrDx is left alone for a while, a queue of un-answered messages builds up, so when you go back after a while, for instance, a few hours, and click into the application, OS X hangs for many seconds while it deals with all the unanswered messages.
However, if the application window is moved, the messages are dealt with — so what Twitch does, when checked, is move the main window up and down one pixel every thirty seconds. This causes OS X to deal with a much smaller number of queued messages, and prevents the long stalls that were occurring.
Note that some graphics hardware does not evidence this problem; for instance, I have a 2/4 core Mac Mini that never stalls. If you're not seeing this kind of UI stall, you don't need to turn on Twitch.
AFEDRI audio slow and draggy sounding
Look at the bottom left of the SdrDx window. Does it say SDR-IP there? If so, your AFEDRI is in RFSPACE Emulation mode. You need to open the AFEDRI-supplied control application and turn "Emulation ID" off. Then it will stop (badly) pretending it is an SDR-IP SDR.
SdrDx Won't let me set the gain on my AFEDRI SDR
Look at the bottom left of the SdrDx window. Does it say SDR-IP there? If so, your AFEDRI is in RFSPACE Emulation mode. You need to open the AFEDRI-supplied control application and turn "Emulation ID" off. Then it will stop (badly) pretending it is an SDR-IP SDR.
This can happen if there is no audio device set. If that's the problem, you can fix it this way: Start SdrDx, click , and select a valid audio output device. Click Okay. SdrDx will close. Changes take effect on next restart.
I get no sound
To clear off anything that might affect audio output, make sure one of , or 
> is on, then that , , , , , , , , , , , 60, 70 and are all off. Make sure is set to the output on your machine that is actually connected to speakers, etc. Make sure that VOL is fully right, I/R is fully left, and you are tuned to an actual signal. Try a local AM BCB station.
The dB scale and/or grid are missing / black
Turn off -- when Automatic Noise Floor is on, the dB and S notations no longer relate to real values, as the noise floor is locked to one vertical position on the display. For this reason, they are not displayed and the measuring grid is set to black. is set to yellow as shown to let you know that the dB scales are disabled.
The scope display is black when I select the audio waterfall
This happens when there is no color palette selected for the waterfall. Press and load one of the supplied audio palettes, or use to create a palette of your own. You can then use to save it under the name pal_defaulta.wfp if you would like this to load automatically when you start SdrDx. If you don't want it to load automatically, save it under a different name.
US CB channels out of order: 22, 24, 25, 23, 26?
This is actually not a problem. If you look at the US CB band below channel 20, you'll see there are gaps every four channels. Those gaps are actually non-voice channels that are intended for industrial and radio control use. Back when there were only 23 CB channels, there was an additional 20 KHz gap (room for two industrial / RC channels) between channels 22 and 23, also intended for that purpose. But years after the 23 channel spacing was finalized when the FCC decided to allow for 40 CB channels, they started just above 22, shoved 24 and 25 in there, skipped where 23 was, and the proceeded upwards at the usual 10 KHz spacing. There's some radio esoterica for you!
Need to get back to "square one?"
Use the "Reset ALL settings and exit" menu command in the File menu. This will give you a totally clean restart.
Versions of Windows often change where they keep program's settings / preferences; so you're kind of on your own figuring that one out. Sorry.
Control-click not working to open dialogs under OS-X?
Check your mouse preferences and make sure that an actual right-click on the mouse is set to work. Then use mouse-right-click, not keyboardControl-left-mouse-click, to open the dialogs. The manual has recently begun to use →Right-click to indicate when you should right-click a button. Remember: a right-click is a right click. Not a control-click.
SDR-14 or SDR-IQ won't connect to server under OS X 10.11
See this note.
or > or is on, SdrDx looks like it's running, but I can't hear any audio
1) Ensure VOL is not at 0
2) Ensure I/R = -120
3) Ensure SQL = 0
11) Make sure the demodulator envelope is wide enough
12) Make sure you're in the proper demodulator mode for the signal
13) If in >, try pressing pause: ||
14) Is blinking? If so, click it or press Spacebar
15) Do you have the correct audio output selected? Check the dialog opened with
With a network SDR, is and won't press
1) Does CUTESDR work in your machine? If not, follow the CUTESDR directions until it does.
2) Is > pressed? You can't be in *and* > .
3) Is pressed? You can't receive on a network SDR and the FUNcube at the same time.
1) SdrDx can't find your FUNcube.
1a) Is the FUNcube plugged in?
1b) Does a virtual machine have a "grip" on it? One client at a time!
1c) Does your FUNcube have the 18j (or later) firmware installed?
is dark green and won't turn bright green
1) Perhaps the sample rate is set too high for some reason. For example, I can't run the full 96000 here on my XP virtual machine; this causes a failure to start. Qt (the development environment) forbids more than 48000 on Windows. But if I set it to 48000, it'll run. Whereas on the Mac, I can run full speed. →Right-click and adjust the sample rate.
FUNcube audio is distorted
1) The FUNcube seems to lose its mind now and then, especially when not used for a while, and a hard reset can often make it work again. Turn it off within SdrDx (click the bright green so it turns dark green ), remove the FUNCube from its USB port ( will turn ), wait 30 seconds, then plug the FUNCube back in. When SdrDx's button again indicates dark green , click it to re-start reception.
2) Sometimes the FUNcube needs to re-adjust its internal AGC. While it does this, it can produce distorted data.
3) Are you tuned to the same demod frequency as the FUNcube's center frequency? Try receiving off to the side. The best achievable DC I/Q balance on the FUNcube isn't great.
4) Make sure that the noise blanker is off: , or, that NBT and NBW are both set to no more than 50. To start with the noise blanker, I recommend NBW=50 and NBT=30
1) Is pressed, and green? Otherwise, record won't work.
1) Is pressed, and green? If so, > play won't work.
2) Is pressed, and green? If so, > play won't work.
1) Is or pressed? You have to be receiving to save waterfalls
My recordings don't work?
1) Is your machine too slow? Try a narrower bandwidth ( / dialog)
My recording files are being split at 500 MB?
1) →Right-click , and set the size you prefer.
It's difficult to set the sliders exactly?
1) Point at the slider knob and try using the mouse-wheel
2) Use TAB and ⇑ TAB to select the slider you want to change, then use ← and →
I can't get the UDP communications going?
1) Make sure the port settings ( dialog) match those in the client application(s.) Also make sure that there is only one UDP client running under OS X, as Apple has a flawed UDP implementation that can only handle one client at a time.
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